Vacuum furnace

ABSTRACT

A vacuum furnace having an oil quenching chamber on one side and a gas chilling chamber on the other side of a heating chamber, while gate means are respectively interposed between the heating chamber and each of the two other chambers for selectively interrupting or permitting communication of the heating chamber with either one of the other two chambers, each of the three chambers being adapted selectively and individually to be evacuated.

United States Patent [191 Limque et a1.

[ 1 June 28, 1974 1 VACUUM FURNACE [75] inventors: Ferdinand Limque, Nijmegen,

Netherlands; Hans Bertrand, Goch, Germany; Irvin P. Bieleteldt, Rockford, Ill.

[73] Assignee: Ipsen Industries International Gesellsehaft mit beschrankter Haftung, Kleve, Germany [22] Filed: Feb. 28, 1972 [21] Appl. No.: 229,903

[30] Foreign Application Priority Data Mar. 1. 1971 Germany 2109507 I52] U.S. Cl. 266/4 A, 266/4 R [51] Int. Cl C2ld 1/62 [58] Field of Search 266/4 R, 4 A, 4 B, 4 E,

266/4 F, 1 R, 5 R

[56] References Cited UNITED STATES PATENTS 3,381,947 5/1968 Beggs 266/4 R 3,684.263 8/1972 Genrich ..266/4A FOREIGN PATENTS OR APPLICATIONS 1,590,606 5/1970 France 266/4 A Primary Examiner-Gerald A. Dost Attorney, Agent, or Firm-Walter Becker 57 ABSTRACT A vacuum furnace having an oil quenching chamber 'on one side and a gas chilling chamber on the other side of a heating chamber, while gate means are respectively interposed between the heating chamber and each of the two other chambers for selectively interrupting or permitting communication of the heating chamber with either one of the other two chambers, each of the three chambers being adapted selectively and individually to be evacuated.

4 Claims, 1 Drawing Figure VACUUM FURNACE The present invention relates to a vacuum furnace for heat treating operations which comprises a heating chamber adapted to be evacuated and a quenching or chilling chamber which is connected to the heating chamber by means of a door opening adapted to be closed in an air-tight manner.

Vacuum furnaces for the heat treatment of metallic objects, for instance bright hardening, annealing, sintering, brazing or stress-free annealing, are known in various forms. Such furnaces are respectively provided with a device by means of which the objects heated in the heating chamber can be quenched or chilled by inert gas or oil 'at given temperature changing speeds. In the simplest instance, cold gas flows around the objects, the charge, in the heating chamber which gas is circulated through the heating chamber after a bottom or ceiling door or gate has been opened. The heating chamber is located within an evacuated pressure container. Inasmuch as in these circumstances the cold gas also passes around the relatively sensitive heating bars of the heating chamber, as a result of which damage might occur, it is also known to provide a gas chilling or quenching chamber which is separated from the heating chamber and is adapted to communicate with the heating chamber through a door opening adapted to be closed in an airtight manner. With such a vacuum furnace comprising two chambers the charge heated in the heating chamber is, after the heating chamber door has been opened, conveyed into the likewise evacuated gas chilling chamber which latter, after the door opening to the heating chamber has been closed, is flooded with inert gas, the temperature of the gas, its circulating speed and the extent to which the gas is cooled being adjustable to any desired value.

The heretofore known vacuum furnaces equipped with an oil quenching or chilling device have an oil bath arranged within a common pressure container adjacent to or below the heating chamber. After the expiration of the heating period, the charge is lowered into the oil bath by means of a conveying device.

All heretofore. known types of vacuum furnaces, aside from the quenching or chilling by means of inert gas or oil, have the drawback that the heating process must be interrupted not only when introducing or withdrawing the charge but also during the chilling or quenching operation so that the heating chamber has to be reheated for each charge at a considerable expense of energy.

It is, therefore, an object of the present invention to provide a vacuum furnace of the above mentioned general character which will make it possible to heat the heating chamber in a continuous manner and which will permit a more flexible treating process.

This object and other objects and advantages of the invention will appear more clearly from the following specification in connection with the accompanying drawing showing an isometric view, partly sectioned, of a vacuum furnace according to the invention.

The vacuum furnace according to the present invention for heat treatment operations having a heating chamber adapted to be evacuated and a quenching or chilling chamber adapted to be connected to the heating chamber through a door opening which is adapted to be closed in an air-tight manner is characterized primarily in that the heating chamber is on two sides respectively connectable to a chilling or quenching chamber adapted to be evacuated and to be separated in an air-tight manner from the heating chamber, while one of the two chilling or quenching chambers is formed as an oil chilling chamber whereas the other one of the two chambers is formed as a gas chilling chamber.

According to a further feature of the present invention, each of the two chambers is adapted to be operated independently of the other chamber. In order to obtain a compact construction, the oil quenching chamber, the heating chamber and the gas chilling chamber are, in conformity with a further feature of the invention, arranged horizontally one behind the other. To permit an automatic working cycle in the vacuum furnace, it is furthermore suggested according to the invention to equip the oil quenching and the gas chilling chamber each with a conveying device adapted to be moved into the heating chamber so that a transport of the charges will be possible between the three chambers while maintaining the vacuum and without opening the vacuum furnace.

Referring now to the drawing in detail, the vacuum furnace according to the present invention has a heating chamber 1 which is arranged in the central portion of the furnace and which has arranged on two opposite sides thereof a gas chilling chamber 2 and an oil quenching chamber 3 respectively. All three chambers 1, 2 and 3 communicate with each other through vacuum conduits 5 with vacuum pumps 4, valves not shown in detail being provided which make it possible that all three chambers 1, 2 and 3 can be evacuated independently of each other.

In the specific embodiment shown, the oil quenching chamber 3, the heating chamber l and the gas chilling chamber 2 are arranged horizontally one behind the other. so that the gas chilling chamber 2 and the oil quenching chamber 3 can be charged from the side. To this end, a conveyor carriage 7 is provided which is movable on rails 6. The separation of the gas chilling chamber 2 or oil quenching chamber 3 from the heating chamber 1 is respectively effected by a lock gate 8 which is adapted by means of a lifting cylinder-piston system 9 to be pulled upwardly from its position shown in the drawing. in closed position, the lock gate 8 will by means of the elbow lever shown in the drawing be able to bring about an air pressure tight separation between the chambers 2 and 3 and the heating chamber 1.

The heating chamber 1 comprises a parallelepiped shaped insulating housing 11 which at both end faces is equipped with upwardly displaceable heating chamber doors 12 adapted to be actuated by a lifting cylinder-piston system 16. Within the insulating housing 11 there is provided a plurality of heating elements 13 which preferably are heated electrically and which are adapted to heat the charges resting on supporting rails 15. In order not to affect the clarity of the drawing, no charges have been shown which charges customarily are contained in so-called charging baskets. The heating chamber 1 which consists primarily of the insulating housing 11 is located in a cylindrical pressure container 14 which at the end faces may be sealed relative to the above referred to lock gates 8.

Thegas chilling chamber 2 primarily comprises a pressure container 21 having a gas inlet 36 and provided with a front door 22 which is adapted to be closed in an air-tight manner. In the interior of the pressure container 21 there is provided a conveying device 23 by means of which a non-illustrated charging basket can be moved into the heating chamber 1 or out of the latter when the lock gate 8 and the heating chamber door 12 are open. The gas chilling chamber 2 is provided with a non-illustrated gas conduit and with heat exchanging means likewise not illustrated which are intended for the inert gas adapted to be blown into the gas chilling chamber 2 for cooling the same. The inert gas is adapted additionally to be circulated by means of a fan 24.

Also the oil quenching chamber 3 is equipped with a pressure container 31 having a gas inlet 36 and adapted to be closed by a front door 32. Below the container 31 there is furthermore arranged an oil container 33 the oil content of which is adapted to be circulated by an oil circulating device 34. A conveying device 35 in the oil quenching chamber 3 makes it possible, in contrast to the conveying device 23 of the gas chilling chamber 2, to charge and discharge heating chamber 1 not only horizontally but also permits a vertical lowering of charging baskets into the oil container 33 for quenching the charge.

By means of the above described vacuum furnace a continuous operation of the heating chamber 1 is possible when the charges are transported through the vacuum furnace in one direction. If, for instance, it is intended to carry out a quenching in oil, the heating chamber 1 is charged through the gasquenching chamber 2 which in such an instance acts merely as a lock. In this way the charge heated in the heating chamber 1 can be transported into the oil quenching chamber 3 in which it can be quenched while at the same time the heating chamber 1 is filled or charged from the gas chilling chamber 2. Inversely, also a continuous opera tion is possible when charging the heating chamber 1 from the oil quenching chamber 3 acting as lock in which instance the quenching is effected in the gas chilling chamber 2 which is cooled by blowing in inert gas.

It is, of course, also possible to operate the vacuum furnace in a non-continuous manner. To this end, the charges are withdrawn from that quenching or chilling chamber 2, 3 through which the charges pass into the heating chamber 1. Thus, it is possible to charge the heating chamber 1 through the oil quenching chamber 3 whereupon, after the charge has been heated in chamber 1, a quenching of the charge is effected in the oil quenching chamber 3 from where the charge is eventually removed by means of the conveyor carriage 7. This con-continuous operation may likewise be transformed into a continuous operation of the heating chamber 1 when the heating chamber 1 is alternately charged from the gas chilling chamber 2 and the oil quenching chamber 3 respectively while each charge is quenched or chilled in that chamber through which is passes into the heating chamber 1.

With each of the above mentioned types of operation, the chilling or quenching in the chamber 2 may be effected slowly at a vacuum or may be accelerated by blowing in inert gas in which instance the inert gas is cooled to a desired extent by the heat exchangers in the chamber 2 and, if desired, may be circulated by the fan 24. In this way there is obtained the possibility of varying the intensity of the gas chilling.

As will be seen from the above, the vacuum furnace according to the present invention will over heretofore known vacuum furnace types permit a considerably shorter charging sequence while at the same time allowing a continuous operation of the heating chamber. This is due to the fact that through the quenching or chilling chambers adapted to be operated as locks and respectively arranged on both sides of the heating chamber it is possible during the quenching or chilling of a charge in one of the quenching or chilling chambers to move the next charge through the other quenching or chilling chamber into the heating chamber. If it is desired, for instance, to quench or chill the charges in the gas chilling chamber, the vacuum furnace is charged through the oil quenching chamber which under these circumstances is employed merely as lock. In this way the continuous cooling off and heating up of the heating chamber will not be necessary so that a considerable saving in costs for the energy to be employed will be realized. On the other hand, the vacuum furnace according to the invention makes it also possible to quench or chill the heated chargesselectively by oil or gas while an alternating operation is possible. Thus, a compact vacuum furnace is obtained which with a high output and relatively low energy costs makes possible different treatment methods.

It is, of course, to be understood that the present invention is, by no means, limited to the particular showing in the drawing but also comprises any modifications within the scope of the appended claims.

What we claim is:

1. A vacuum furnace for heat treating operations, which includes: a heating chamber, two chilling chambers respectively arranged on opposite sides of said heating chamber for selective communication with each other, one of said chilling chambers being a gas chilling chamber and the other one of said chilling chambers being an oil quenching chamber, evacuating means operatively connectable to any one of said chambers for selectively evacuating the same, and gate means interposed between said heating chamber and said chilling chambers and operable selectively to interrupt and permit communication of said heating chamber with either one and with both of said chilling chambers.

2. A vacuum furnace according to claim 1, which includes means associated with all of said chambers for selectively operating each chamber independently of each other.

3. A vacuum furnace according to claim 1, in which said oil quenching chamber and said heating chamber and said gas chilling chamber are arranged horizontally one behind the other.

4. A vacuum furnace according to claim 1, which includes charging means respectively associated with said oil quenching chamber and said gas chilling chamber and selectively movable into said heating chamber. 

1. A vacuum furnace for heat treating operations, which includes: a heating chamber, two chilling chambers respectively arranged on opposite sides of said heating chamber for selective communication with each other, one of said chilling chambers being a gas chilling chamber and the other one of said chilling chambers being an oil quenching chamber, evacuating means operatively connectable to any one of said chambers for selectively evacuating the same, and gate means interposed between said heating chamber and said chilling chambers and operable selectively to interrupt and permit communication of said heating chamber with either one and with both of said chilling chambers.
 2. A vacuum furnace according to claim 1, which includes means associated with all of said chambers for selectively operating each chamber independently of each other.
 3. A vacuum furnace according to claim 1, in which said oil quenching chamber and said heating chamber and said gas chilling chamber are arranged horizontally one behind the other.
 4. A vacuum furnace according to claim 1, which includes charging means respectively associated with said oil quenching chamber and said gas chilling chamber and selectively movable into said heating chamber. 